Re: staining plastic-embedded sections

From:

"J. A. Kiernan" <jkiernan@julian.uwo.ca>

On Thu, 5 Oct 2000, Andrea Voogt wrote:
> I'm a college student doing a research project on the histology of the
> garter snake digestive tract and associated glands. I already have
> tissues embedded in plastic, but all the books I can find have staining
> procedures for paraffin. Does anyone know the staining procedures for
> plastic-embedded tissues? The stains I'm hoping to use include
> Mallory-Heidenhain's azan, Best's carmine, Gomori's chrome alum
> hematoxylin-phloxine, Iron-hematoxylin and thiazine red staining,
> Bielschowsky-Foot's method, and Masson's stain, but methods for any
> stains that would be good for digestive tract and associated organs
> would be much appreciated!!!
This is a pretty tall order for a beginner! Some of those stains
can be difficult to get right on paraffin sections (for which they
are all intended), and you cannot simply apply the same procedure
to plastic. You mention that the plastic is JB-4. This is glycol
methacrylate (I think) and it has a chemically cross-linked molecular
structure, so it cannot be dissolved out of the plastic. The
embedding medium interferes with penetration of dyes and other
reagents, and also with the dye-tissue specificities.
Fortunately It is possible to cut plastic sections thinner than
paraffin ones, and with a really thin section (say, 1 to 2 micrometres)
you can see plenty of structural detail with just one dye that
stains everything. An alkaline solution of toluidine blue is
often used.
There are published variants of older staining methods that you
can use with glycol methacrylate embedding, and I'm sure you'll
get plenty of good suggestions from the listserver, but I'd
advise trying something very simple first, and not trying to
bite off what might turn out to be too much to chew. Good luck.
John A. Kiernan,
Department of Anatomy & Cell Biology,
The University of Western Ontario,
LONDON, Canada N6A 5C1